Metallogeny is the branch of geology that seeks to define the genetic relationships between the geological history of an area and its mineral deposits. Mineral deposits, in the broadest sense, form part of the same geological record as less-valuable rocks, and were deposited in response to processes in the same geological and tectonic environ- ments. Mineral deposit studies both contribute to and bene- fit from understanding of the regional geological and tectonic development of an area. The deposits in some cases provide important data as to the geological processes opera- tive at different times. On the other hand, regional geological models are essential to help constrain possible met- allogenic models, when a large number of deposits having formed at several different times are present.

As recognized many years ago by McCartney and Potter (1962), the Canadian Appalachians provide a particularly good laboratory for the study of regional metallogeny. The regional geology is relatively well understood and inter- preted in terms of well constrained tectonic models and a wide variety of mineral deposit types and ages provide a record of mineralization that spans the entire history of the orogen. This chapter considers the nature of the mineral deposits in the Canadian Appalachians and their place in the geological and tectonic framework of the orogen.

The concept of metallogeny, as distinct from economic geology, was pioneered by de Launay (1900, 1913) who identified consistencies in the regional geographical variations in the occurrence of ores. Perhaps his major contribution was the introduction of